Ole Böstman

Foreign-body reactions to fracture fixation implants of biodegradable synthetic polymers

Biodegradable rods of polyglycolide or lactide-glycolide copolymer were used in the internal fixation of a variety of fractures and osteotomies in 516 patients. A clinically manifest foreign-body reaction occurred in 41 patients (7.9%), producing a fluctuant swelling at the implantation site after an average of 12 weeks. Spontaneous sinus formation or surgical drainage yielded a sterile exudate containing liquid remnants of the degrading implants. After prompt drainage this discharge subsided within three weeks. Histological examination showed a typical nonspecific foreign-body reaction with abundant giant cells both in patients with the reaction and in some patients with an uneventful clinical course. The factors determining the nature of the reaction were probably related to the local capacity of the tissues to clear the polymeric debris. The reactions did not influence the clinical or radiographic results, but recognition of the incidence and the features of the reaction is necessary in view of the increasing use of such implants.

Bioabsorbable fixation in orthopaedic surgery and traumatology

Bioabsorbable internal fixation devices were introduced clinically in the treatment of fractures and osteotomies of the extremities at the Department of Orthopaedics and Traumatology, Helsinki University, in 1984. Since November 5, 1984, a total of 3200 patients were managed using bone or ligament fixation devices made of self-reinforced (matrix and fibres of the same polymer) bioabsorbable alpha-hydroxy polyesters. The devices used included cylindrical rods, screws, tacks, plugs, arrows, and wires. The most common indication for the use of bioabsorbable implants was the displaced malleolar fracture of the ankle. Transphyseal fixation with small-diameter, mainly polyglycolide pins was used in children. The postoperative clinical course was uneventful in more than 90% of the patients. The complications included bacterial wound infection in 4% and failure of fixation in 4%. In one-fifth of the latter cases, however, re-operation was not necessary. The occurrence of non-infectious foreign-body reactions two to three months postoperatively has been observed in 2% of the patients operated in the last few years with polyglycolide implants but none of the patients managed with polylactide implants. This inflammatory tissue response often required aspiration with a needle but did not influence the functional or radiologic result of the treatment. Owing to the biodegradability of these internal fixation devices, implant removal procedures were avoided. This results in financial benefits and psychological advantages. Bioabsorbable implants can also be used in open fractures and infection operations.

Osteolytic changes accompanying degradation of absorbable fracture fixation implants

We analysed the radiographs of 67 patients with displaced malleolar fractures treated by open reduction and internal fixation using absorbable polyglycolide rods. Seventeen patients developed a discharging inflammatory foreign-body reaction, a complication unique to these fixation devices. In 34 patients ovoid osteolytic foci, usually 5 to 10 mm in diameter, appeared within the implant channels six to 12 weeks after the operation. The same lesion occurred in 14 of the 17 patients who developed a foreign-body reaction, whereas only 20 out of the 50 patients with an uneventful course showed osteolytic areas (p less than 0.01). In patients with a foreign-body reaction the osteolytic foci tended to occur in the deepest parts of the implant channels. However, after one year the normal structure of the bone was restored.

Complications of plate fixation in fresh displaced midclavicular fractures.

BACKGROUND The role of plate fixation in the management of fresh displaced midclavicular fractures is unsettled. The objective of this study was to evaluate the drawbacks and pitfalls of this treatment method. METHODS We analyzed the complications encountered in 103 consecutive adult patients with severely displaced fresh fractures of the middle third of the clavicle who were treated by open reduction and internal fixation using AO/ASIF plates. These 103 patients accounted for 9.5% of the 1,081 patients with fresh midclavicular fractures seen between 1989 and 1995. The mean age of the 103 patients was 33.4 years (range, 19-62 years). RESULTS Seventy-nine patients had an uneventful recovery, whereas 24 (23%) suffered one or several complications. The major complications included deep infection, plate breakage, nonunion, and refracture after plate removal. The most common of the minor complications was plate loosening resulting in malunion. The infection rate was 7.8%. A total of 14 reoperations were performed because of the complications. Permanent nonunion ensued in two patients. A severely comminuted fracture (relative risk of failure, 5.15) as well as a state of alcohol intoxication on admission (relative risk of failure, 3.12) were identified as markers of increased complication risk. CONCLUSIONS Patient noncompliance with the postoperative regimen could be suspected to have been a major cause of the failures. The high complication rate supports a reserved attitude toward plate fixation of fresh midclavicular fractures. The method should be reserved for patients who have trustworthy personal motives for quick pain relief and functional recovery.

COMPLICATIONS OF TRANSPEDICULAR LUMBOSACRAL FIXATION FOR NON-TRAUMATIC DISORDERS

We analysed the complications encountered in 102 consecutive patients who had posterolateral lumbosacral fusion performed with transpedicular screw and rod fixation for non-traumatic disorders after a minimum of two years. Of these, 40 had spondylolysis and spondylolisthesis, 42 a degenerative disorder, 14 instability after previous laminectomy and decompression, and six pain after nonunion of previous attempts at spinal fusion without internal fixation. There were 75 multilevel and 27 single-level fusions. There were 76 individual complications in 48 patients, and none in the other 54. The complications seen were screw misplacement, coupling failure of the device, wound infection, nonunion, permanent neural injury, and loosening, bending and breakage of screws. Screw breakage or loosening was more common in patients with multilevel fusions (p < 0.001). Screws of 5 mm diameter should not be used for sacral fixation. Forty-six patients had at least one further operation for one or several complications, including 20 fusion procedures for nonunion. The high incidence of complications is a disadvantage of this technically-demanding method.

Failure of reduction with an external fixator in the management of pelvic ring injuries: LONG-TERM EVALUATION OF 110 PATIENTS

We reviewed 110 patients with an unstable fracture of the pelvic ring who had been treated with a trapezoidal external fixator after a mean follow-up of 4.1 years. There were eight open-book (type B1, B3-1) injuries, 62 lateral compression (type B2, B3-2) and 40 rotationally and vertically unstable (type C1-C3) injuries. The rate of complications was high with loss of reduction in 57%, malunion in 58%, nonunion in 5%, infection at the pin site in 24%, loosening of the pins in 2%, injury to the lateral femoral cutaneous nerve in 2%, and pressure sores in 3%. The external fixator failed to give and maintain a proper reduction in six of the eight open-book injuries, in 20 of the 62 lateral compression injuries, and in 38 of the 40 type-C injuries. Poor functional results were usually associated with failure of reduction and an unsatisfactory radiological appearance. In type-C injuries more than 10 mm of residual vertical displacement of the injury to the posterior pelvic ring was significantly related to poor outcome. In 14 patients in this unsatisfactory group poor functional results were also affected by associated nerve injuries. In lateral compression injuries the degree of displacement of fractures of the pubic rami caused by internal rotation of the hemipelvis was an important prognostic factor. External fixation may be useful in the acute phase of resuscitation but it is of limited value in the definitive treatment of an unstable type-C injury and in type-B open-book injuries. It is usually unnecessary in minimally displaced lateral compression injuries.

Deep venous thrombosis and pulmonary embolism in patients with acute spinal cord injury: a comparison with nonparalyzed patients immobilized due to spinal fractures

The occurrence of deep venous thrombosis (DVT) was studied in the series of 23 consecutive patients with acute spinal cord injury and 14 immobilized patients with spinal fractures without paralysis. The incidence of DVT in paralyzed patients was 100% as detected by the 125I-labeled fibrinogen test and confirmed by contrast venography, and 64% as detected by repeated clinical examinations and confirmed by contrast venography. The respective incidence of DVT in nonparalyzed patients with spinal fractures was 0%. The diagnosis of DVT was reached earlier with the radiofibrinogen test than with the clinical followup (5 days vs. 25 days). Two of the 23 paralyzed patients (9%) developed nonfatal clinical pulmonary embolism (PE). There were no differences in the values of routine coagulation tests. The result justifies prophylactic anticoagulant therapy in all cases of spinal cord injury during the acute post-traumatic phase.

Routine implant removal after fracture surgery: a potentially reducible consumer of hospital resources in trauma units.

OBJECTIVE Assess the workload caused by elective routine removals of internal fracture fixation devices in a large university orthopedic and trauma unit when no premeditated departmental removal policy existed. MATERIALS AND METHODS Data on all operations performed during a 7-year period were retrieved. Routine removals of internal fracture fixation implants were analyzed for demographic data and clinical details. Patients requiring additional procedures to manage the fracture besides simple hardware removal were excluded. Nationwide data were included for comparison. RESULTS A total of 5,095 routine implant removal operations were performed after uneventful fracture union. The mean age of the patients was 42 years. The five most common fracture types were fractures of the ankle, the proximal femur, the tibial shaft, the femoral shaft, and the thoracolumbar spine. In 63% of the procedures, a medium-size or large implant was removed. The mean operation time was 37 minutes. The removals accounted for 29% of all elective operations and for 15% of all operations at the department. The corresponding nationwide figure was 6.3% of all orthopedic operations, the number of implant removals in the whole country being 90 operations per 100,000 person-years. CONCLUSIONS Without a strict departmental removal policy, a remarkable portion of the resources allocated for elective orthopedic operations was spent on routine hardware removal procedures. A more rational and selective attitude toward implant removals is desirable. Further research on the disadvantages of retained hardware and the complications of implant removals is required.

Ankle fractures treated using biodegradable internal fixation.

In order to reduce the resources needed for the removal of metallic fixation devices in fracture treatment, absorbable implants of biodegradable synthetic polymers were developed using self-reinforced lactide-glycolide copolymer and polyglycolide. In a prospective study 102 patients with displaced unimalleolar or bimalleolar fractures of the ankle were managed using internal fixation devices consisting of cylindrical biodegradable implants 3.2 or 4.5 mm in diameter and 50 or 70 mm in length. After open reduction of the fracture a channel was drilled from the tip of the malleolus into the cancellous bone through the fracture surfaces. A biodegradable rod of the same diameter was then tapped into the drill channel to fix the fracture. Postoperatively, the ankle was immobilized by a plaster cast for six weeks. An anatomic initial reduction was achieved in 93 patients (91%). A slight secondary displacement occurred in four patients. In six patients a sinus formation yielding remnants of the degrading implant was seen two to four months after the operation. This minor complication did not influence the union of the fracture or functional recovery. At the one-year follow-up examination there was no change in the ability to participate in sports and other physical activities in 89 patients (87%). The biodegradable fixation method is now the routine approach of the department in treating displaced unimalleolar and bimalleolar ankle fractures. New clinical applications for the implants are under trial.

Absorbable pins of self-reinforced poly-L-lactic acid for fixation of fractures and osteotomies

We reviewed 27 patients with small-fragment fractures or osteotomies treated by internal fixation with absorbable self-reinforced poly-L-lactide pins. The follow-up time ranged from eight to 37 months. The two most common indications were chevron osteotomy of the first metatarsal bone for hallux valgus and displaced fracture of the radial head. No redisplacements occurred, and there were no signs of inflammatory foreign-body reaction. Biopsy in two patients 20 and 37 months after implantation showed that no polymeric material remained.